Production of electrical variations



C. G. SMITH PRODUCTION OF ELECTRICAL VARIATIONS Feb. 8, 1927.

Filed Oct. 8, 1920 2 Sheets-Sheet 1 Feb. 1927.-

c. 0. SMITH PRODUCTION OF ELECTRICAL VARIATIONS Filed Oct. 8. 1920 2 Sheets-Sheet 2 Patented Feb."'8, 1927.

UNITED STATES PATENT. OFFICE.

CHARLES e. SMITH, or mnnronn, massscnosnr'rs, ASSIGNOR, BY .unsna ASSIGN- MENTS, TO RAYTHEON MANUFACTURING COMPANY, OF SETTS, A CORPORATION OF MASSACHUSETTS.

CAMBRIDGE, MASSACHU- PRODUCTION OF ELECTRICAL VARIATIONS.

Application filed October 8, 1920. Serial No. 415,587.

The present invention relates to a method and apparatus "for producing energy variations in electrical circuits.

According to a copending Patent .No. 1,545,207, granted July 7, 1925, a new form of insulating gap embodying a gaseous medium has been disclosed. In this apparatus the use of properly designed and located electrodes immersed in a gas aflords paths for the passage of electrons through the gas too short to permit substantial ionizatlon to take place. As disclosed in said patent, this result is secured by spacin the active surfaces of the electrodes at ifi'erent potentials a relativel short distance apart, the space separating these surfaces being of the order of magnitude of the mean free path of the electrons to avoid collision of electrons, and atoms and consequent electric discharge. In addition all paths through the insulating dielectric which are subject to a potential gradient are made sufiiciently long to prevent breakdown.

I have discovered that it is possible to vary the path of travel of the electrons in a manner to render an otherwise insulating gap conducting and to, in addition, vary the conductivity of the gap as desired. In the best form of the invention now known, the operation of the gap maybe controlled by the interposition of a fluctuating magnetic field in the space between the electrodes which may distort the path of travel of the electrons sufficiently to make the gap alternately conducting and nonconducting.

The inherent capacity of the gap to vary in conductivity in accordance with the variations in a magnetic field permits the apparatus to be utilized as a relay or amplifier when provided with an output circuit containing the electrodes and an input circuit arranged to vary the magnetic field between the electrodes, the fluctuations of energy in the output circuit being caused by the fluctuating magnetic field. If the input circuit be connected with the output circuit in a manner to cause the fluctuations of the magnetic field to be derived from the output circuit then the apparatus may be employed as an oscillator or generator of alternating currents.

One feature of the present invention accordingly consists in the embodiment of two electrodes immersed in a gas and having their active surfaces located in sufiiciently close proximity to normally prevent electric discharge through the gas at a given potential with means for varying the normal path of travel of the electrons through the gas to accordingly vary the conductivity of the apparatus.

A further feature of the invention consists in the use of a fluctuating magnetic field in the space between the electrodes to vary the conductivity of the space and cause the excitation of alternating current either in a circuit including the electrodes directly or in a circuit inductlvely or otherwise coupled to the above circuit.

In a simple and efficient mechanical embodiment of the invention two electrode tubes of different diameters are located in concentric relation with all portions of their active surfacesat difl'erent potentials located in close proximity. These tubes are immersed in a gas which is sub'ected to a fluctuating magnetic field create in any suitable manner. This magnetic field may fluctuate in a manner to alternately render the tube conducting or nonconducting or in a manner to vary the conductivity of the tube without causing it to become totally nonconducting to the impressed voltage.

In the accompanying drawings illustrating one embodiment of the invention Fig. 1 represents a section in elevation of a tube embodying the principles of the invention; Fig. 2 is diagrammatic view of a circuit arrangement in which the input circuit, including the means for creating the magnetic field, derives its energy from the output circuit, including the electrodes; Fig. 3 is a slightly modified form of Fig. 1 illustrating the use of a permanent magnet for the creation of a constant magnetic field with a coil for imposing an additional fluctuating increment of magnetic field; and Fig. 4 is a diagrammatic view illustrating a suitable circuit arpiangement when using the tube as an ampli- According to the illustrated embodiment of the invention, two electrode tubes 10 and all lating supports 16 and 18, forming an integral part of the base of the vessel. The inner and outer tubes are respectively connected with leads 20 and 22 which pass out of the containing receptacle in such a manner that there is no possibility for short circuit through the insulating dielectric. The electrode tubes which are under a potential difi'erence are so designed and located with respect to one another that there is normally no gaseous conduction between them. This insulating property of the tubes is due to the fact, as previously explained, that the distance separating the surfaces of the tubes under a potential difference is of the order of magnitude of the normal mean free path of the electrons.

The region separating the active surfaces of the tubes is subjected to a fluctuating magnetic field to vary the conductivity of the tube as a whole. This may be conveniently accomplished'by the provision of an electro-ma et 24 designed to create a constant field and additional coils 26 located having a source of potential 36 an including the electrodes10 and 12, the variations in the conductivity of the tube thus produced will act upon the output circuit in a corresponding manner and cause the tube to operate as a relay or amplifier, the fluctuations of energy thus produced being utilized by any desired form of circuit.

It is possible that by connecting an input circuit 32 with an output circuit 29, as shown in Fig. 2, so that thefluctuations in the magnetic field are excited through back connection from the output circuit,'the tube may be caused to act as a latory currents.

-Itwill -be obvious to those skilled in the art that the constant magneticfield may be created. either through an electro-magnetic coil, as shown in Fig. 1, or by a permanent magnet 40 of suitable form, as indicated in generator of oscil- Fig. 3. If it is desired to vary theiutensity of the field produced by this permanent magnet, an armature 41 may. be adjustably connected with the opposite poles of the magnet through adjusting members 44 and 45 in such a 'manner that by movingthe armature toward and from the magnet the desired adjustment of-field strength may be obtained,

Whenthe tube is conducting, the bombardment of the surfaces of the electrodes may give rise to some disintegration of the latter and while the loss of metal in itself is-not of importance the spattering of the metal upon the insulating dielectric may eventual y cause short circuits and consequent breakdown of the tube. To avoid possibility of such an occurrence, it is desirable to localize the re ion of discharge 7.

between the surfaces of t e electrodes and this is accomplished in the illustrated embodiment of the invention by localizing the magnetic field, as will be observed from an inspection of Figs. 1 and 2 of the drawings. Owing to the construction and arrangement of the magnets with respect to the tube, the field is localized at adistance from the insulating su iportsin such a manner that the discharge well away from the supports.

It is important for the successful operation of'apparat'us of this character that the gas pressure within the receptacle shall be maintained substantially constant. If it were necessary I to maintain a perfect vacuum or a nearly erfect vacuum, as in the case of the usua thermionic tubes, it would benecessary for the enclosing vessel to be carefullyv constructed of material impervious to'the leakage of gas therethrough, but as the .present apparatus will operate successfully with a considerable gas pressure, especially when employing some form of inert gas, it is feasible to malntain a substantially constant pressure even when-using metal or other enclosing receptacles through, which -intolerable leakage would ordinarily occurif operating with a substantially perfect vacuum. To insure maintenance of the best operating gas pressure it is-preferable to completely remove from the tube all active ases that would ordinarilylcombine with t e electrode material and condense on the walls of the (am closing vessel and fill the tube with an inert gas. The insulating ring 16 serves the twofold purpose of supporting the outer electrode. and localizing the electrical pile-115 nomena accompanying the gaseous discharge within the hollow electrode. Bvex- ,tending the insulation 16 longitudinally of etween the electrodes occurs s.

same as that between the two electrodes) the 5 normal tendency ofthe discharge to seek the junction between the smaller electrodeand the insulation is minimized.' H v Referring to Figure 3 the hollow cathode 10 has an openingin its lower end' ta'cing the reentrant stem 18 which supports the anode 12, and the insulation material 16 bridges the space between the hollow cathode and the conductor 20, which conducts current to the anode,12, whereby the aforesufficiently close proximity to each other to normally prevent gaseous conduction and means for creating a fluctuating magnetic field which extends transversely of lines bridging the space between the electrodes to vary the conductivity of the gaseous medium in accordance with the fluctuations in the magnetic field.

2. An electrical apparatus comprising a gas-filled receptacle, electrodes supported within the receptacle at different potentials and having their surfaces separated a distance approximating the normal mean free path of electrons in the gas to normally prevent gaseous conduction, and means for producing a magnetic field of varying intensity transversely in the space between the electrodes to render the conductivity of the gap Variable in accordance with the fluctuations in the field. 1

3. An electrical apparatus comprising a gas-filled receptacle, electrodes mounted within the receptacle, supporting means for holding the electrodes in spaced relation with their surfaces positioned in close proximity to each other to normally prevent gaseous conduction, and means for creating a fluctuating magnetic field transversely in the space between the electrodes to permit fluetuating electric discharge through this space in response to potential difference between electrodes.

4. An electrical circuit including two spaced electrodes immersed in a gas and having their surfaces at different potentials separated a distance approximating the normal mean free path of electrons in the gas to normally prevent gaseous conduction, means for creating a magnetic field transversely in the space separating the electrodes and means for impressing another variable field upon the magnetic field thus created periodically to permit conduction between the electrodes in response to said difference in potential. v

5. An electrical apparatus comprising a gas-filled receptacle, spaced electrodes enclosed within the receptacle, a circuit in cluding the electrodes and gas in which they are immersed, the electrodes having their apparatus comprising .electrodes immersed in a gas and located in surfaces located in close proximity. to each.

other to normally prevent electric discharge through the gas, and means to cause pulsating conduction through the gas.

6. An electrical apparatus comprising a. gas-filled receptacle, concentric electrode tubes enclosed Within the receptacle means for supporting and locating the tubes, the 1 tubes being designed and arranged to normally prevent gaseous conduction, and m for creating afluctuating mag 11mg: through a portion of the gas re 'oved from the supporting means periodic ly to permit gaseous conduction between corresponding portions of the electrode tubes in res onse to potential differences between electro es.

7. An electrical apparatus comprising a gas-filled receptacle, concentric electrode tubes enclosed within the'receptacle, means for supporting and locating the tubes in a manner to normally prevent gaseous conduction, and variable means to permit pulsating gaseous conduction to take place be,- tween a restricted portion of the tubes in response to potential difference between the electrodes.

8. An electrical apparatus comprising two electrodes immersed in a gas and located in sufficiently close proximity to normally prevent gaseous conduction, a circuit connected to the electrodes and including a source of potential and a second circuit designed to create a magnetic field in the region separating the surfaces of the electrodes and connected to the first mentioned circuit in a manner to be influenced thereby.

9. An electrical apparatus comprising a' gas filled receptacle, electrodes enclosed in the receptacle and having active opposing surfaces separated a distance comparable to the mean 'free path of electrons in the gas,

path lengthening means for increasing the paths of electrons passing between the electrodes to cause gaseous ionization and conduction. and means for periodically varying the path lengthening means tocause similar variations in the conductivity of the gas.

10. An electrical apparatus comprising a gas filled envelope, cooperating electrodes received within the envelope and having their opposed surfaces spaced apart a distance approximating the order of magnitude of the mean free path of electrons in the gas, an electric circuit including the electrodes, and means including another electric circuit for varying the conductivity of the gaseous space separating the electrodes.

11. An electrical apparatus comprising a gas filled envelope, cooperating electrodes received within the envelope and having their opposing surfaces spaced in sufficiently close proximity to prevent gaseous conduction therebetween, an electric circuit including the electrodes, and means for creating a fluctuating magnetic field transversely in the gaseous space separating the surfaces of the electrodes. I

12. An electrical apparatus comprising a gas filled receptacle, a pluralit of electrodes in the receptacle having sur aces .spaced a distance comparable to the mean free path for producing gaseous conduction between said electrodes, and means responsive to said gaseous conduction for impressing a variable magnetic field upon the space between the electrodes, thereby to vary the conduction path between electrodes.

14. A gaseous conduction device comprising a hollow electrode closed except for an opening in one end, another electrode presented to the interior of the hollow electrode through said opening, and variable magnetic means for varying the state of ionization of the gas inside the hollow electrode, thereby to control the current flow between the two electrodes.

15. The method of producing pulsating gaseous conduction between two electrodes spaced sufficiently close normally to prevent conduction therebetween, which comprises concomitantly impressing electric and magnetic fields upon the space between the electrodes and recurrently varying the state of ionization of the gas by varying the magnetic field, thereby to render the path between the two electrodes alternately conducting and relatively non-conducting.

16. A aseous conduction device compris ing a tu e having a reentrant stem at one end, a hollow cathode in the tube with an o enin therein facin said stem an anode surface supported by said stem and pre sented to the interior of the hollow cathode, aconductor for conducting current to the anode surface, and insulation material bridging the space between the hollow cathode and conductor, whereby the opening is closed.

17. A gaseous conduction device comprising a tube having a reentrant stem at one end, a hollow cathode in the tube with an opening therein facing said stem, an anode :surface supported by said stem within the hollow cathode, a conductor extending through said opening for conducting current to the anode surface, and insulation mate- 'rial bridging the space between the hollow cathode and conductor.

A 18. An electrical discharge device comprising electrodes having discharge surfaces presented to each other across an intervening gas space, and insulating material exone of said surfaces adjacent said space in I spaced relation to the surface, the gap between the surface and the shield being substantially confined to the mean free path of electrons in the gas.

20. An electrical discharge device comprising electrodes presented to each other across an intervening gas space, one electrode being smaller than the other, and insulation surrounding the smaller electrode adjacent said space in spaced relation to its outer surface, the gap between said surface and the insulation being substantially coufined to the mean free path of electrons in the gas.

21. A gaseous conduction device comprising a hollow electrode having an opening therein, a smaller electrode extending into said opening, and insulation surrounding the smaller electrode in spaced relation thereto adjacent said opening, the gap between said smaller electrode and insulation being substantially confined to the mean free path of electrons in the gas.

22. A gaseous conduction device comprising a tubular electrode having an open end, a cylindrical conductor extending into said open end and terminating in an electrode surface within the hollow electrode, and an insulating ring surrounding said conductor in spaced relation thereto adjacent said openmg, the gap between the conductor and rlng being substantially confined to the mean free path of electrons in the gas.

23. A gaseous conduction device comprising a receptacle having a reentrant stem and containing two electrodes, an insulating ring surrounding said stem with a gap therebetween comparable to the mean free path of electrons in the gas, a lead to one electrode extending through said stem and the other electrode being mounted on said ring.

24. A gaseous conduction device comprising a receptacle having a reentrant stem, an electrode mounted on said stem, an insulation ring surrounding said stem with a gap therebetween comparable to the mean free path of electrons in the gas, said ring being integrally joined to said stem at the end of the rin nearest the base of the of the stem and extending along the pestem, and anot er electrode mounted on riphery of the stem in close juxtaposition said ring. thereto, an electrode conductor extending 10 25. A gaseous conduction device compristhrough the stem, and an electrode mounted 5 ing a glass receptacle having a reentrant on the ring.

stem, :1 glass rin integrally joined to the stem at the end 0 the ring nearest .the base CHARLES G. SMITH. 

